Afterburner

ABSTRACT

An afterburner for completing the combustion of stack gases and the like has a fuel supply to the interior of the stack and a mechanically controlled pilot which is blown by a jet of gas into the stack to ignite the fuel. The jet flows in parallel with the fuel supply. The pilot and fuel emerge centrally in the stack and are deflected by a downwardly concave deflector that cooperates with a larger upwardly concave deflector. An annular downwardly opening hood surrounds the stack and shields the pilot and the secondary air inlets.

United States Patent 2,480,230 8/1949 Elster 2,696,875 12/1954 Henwood Primary Examiner- Edward G. Favors Attorney-Young & Thompson ABSTRACT: An afterburner for completing the combustion of stack gases and the like has a fuel supply to the interior of the stack and a mechanically controlled pilot which is blown by ajet of gas into the stack to ignite the fuel. The jet flows in parallel with the fuel supply. The pilot and fuel emerge centrally in the stack and are deflected by a downwardly concave deflector that cooperates with a larger upwardly concave deflector. An annular downwardly opening hood surrounds the stack and shields the pilot and the secondary air inlets.

PATENTEB D5121 um SHEET 1 BF 2 m ww Ll (A e e .V mw A m aw AFTERBURNER The present invention relates to afterburners, more particularly of the type that aid in completing the combustion of stack or flue gases.

It is an object of the present invention to provide an afterburner for the more complete combustion of stack or flue gases, which is especially well adapted for application to an upright stack.

Another object of the present invention is the provision of such an afterburner which will be both easy and safe to light.

Finally, it is an object of the present invention to provide an afterburner which will be relatively simple and inexpensive to manufacture, easy to install, operate, maintain and repair, and rugged and durable in use.

Other objects and advantages of the present invention will become apparent from a consideration of the following description, taken in connection with the accompanying drawings, in which:

FIG. 1 is a side cross-sectional view of an afterburner according to the present invention;

FIG. 2 is a perspective view of an incinerator with an afterburner according to the present invention installed on the stack thereof;

FIG. 3 is a perspective view of the lower deflector of the afterburner of the present invention;

FIG. 4 is a side view in the direction of fuel supply, of the afterburner of the present invention with the downwardly opening annular hood removed; and

FIG. 5 is atop plan view of the structure shown in FIG. 4.

Referring now to the drawings in greater detail, there is shown an afterburner according to the present invention, indicated generally at l and comprising an upright sleeve 3 slidably removably supported on the stack of an incinerator 5 which may for example be of the type shown in copending application Ser. No. 686,452, filed Nov. 29, 1967. Sleeve 3 comprises an upward extension of the stack, and the term stack" that appears in the claims comprises both a removable sleeve and an integral stack.

The afterburner includes a downwardly opening annular hood 7 comprising a vertical cylindrical skirt 9 and a conical top 11 whose inner circular edge rests on an angle 13 which is secured to sleeve 3 as by welding, brazing, riveting or the like. In order to locate hood 7 in a predetermined position on the stack, angle 13 carries an upwardly projecting locator pin 15 that fits in a single corresponding hole in top 11. Hood 7 and the parts carried thereby are thus removable from the stack simply by raising them axially of the stack. When in place, however, hood 7 serves not only to protect portions of the afterburner, but also to shield the inlet openings 17 for secondary air.

A bracket 19 is secured to and declines outwardly from top 11 of hood 7 and supports at its outer end a housing 21 for the fuel valve 23. In the illustrated embodiment, a gaseous hydrocarbon fuel is contemplated, which reaches valve 23 through a fuel supply line 25 and proceeds from valve 23 through a U-shaped line 27 to a horizontally directed main gas orifice 29 and a horizontally directed auxiliary gas orifice 31 disposed thereabove and in parallel fluid circuit therewith. Orifice 29 directs the fuel into the cone 33 of a pipe 35 which extends horizontally through the sidewall of sleeve 3 and terminates in an upwardly extending outlet 37 which constitutes a burner proper for the afterburner. Outlet 37 carries an annular upwardly concave disc 39 whose edges are serrated and also a superposed downwardly concave disc 41 of smaller diameter than disc 39. The path of gas flow, with air admixed therein, is thus upwardly out of outlet 37 and then downwardly under the deflection of disc 41, and then upwardly and outwardly again under the deflection of disc 39.

A pilot 43 is supplied with gaseous fuel continuously through a line 45 and discharges its fuel in the path of orifice 31. A thermocouple 47 adjacent and carried by pilot 43 detects elevated temperature to maintain valve 23 open through line 49, and responds to low temperature to close valve 23.

Thus, valve 23 is closed unless the pilot is li hted.

The stream of gas from orifice 3 blows e flame from pilot 43 through a tube 51 that is secured at its outer end in and passes through sleeve 3 and that rests on its inner end on disc 39. Thus, any time that valve 23 is open and the fuel supply is entering the afterburner through orifice 29, a smaller stream of gas issuing from orifice 31 will blow the pilot light through tube 51 to ignite the afterburner. When the pilot is extinguished, then thermocouple 47 will maintain valve 23 closed. Thus the pilot can be safely lighted if it is extinguished, because valve 23 will necessarily be closed at that moment. Access to pilot 43 is had through a pivotally mounted door 53 in the side of skirt 9.

From a consideration of the foregoing disclosure, therefore, it will be evident that all of the initially recited objects of the present invention have been achieved.

Although the present invention has been described and illustrated in connection with a preferred embodiment, it is to be understood that modifications and variations may be resorted to without departing from the spirit of the invention, as those skilled in this art will readily understand. Such modifications and variations are considered to be within the purview and scope of the present invention as defined by the appended claims.

Having described my invention, I claim:

1. An afterburner for a stack, comprising a pilot light outside the stack, a tube for fuel extending into the stack, means for blowing flame from the pilot light through a wall of the stack and into the path of fuel emerging from said tube, and means to supply gaseous fuel to said tube, said supply means also blowing gaseous fuel across the pilot light and through said wall of the stack.

2. An afterburner as claimed in claim I, said fuel supply means comprising a pair of orifices in parallel fluid circuit with each other, one of said orifices being larger than the other and supplying gas to said tube, and the said other orifice blowing across the pilot light.

3. An afterburner as claimed in claim 2, and a downwardly opening annular hood encompassing said stack and covering said orifices and pilot light.

4. An afterburner as claimed in claim 3, and means removably mounting said hood on the stack.

5. An afterburner as claimed in claim 4, said removable mounting means comprising a support carried by the stack, the inner margin of the hood resting on said support, one of said support and margin having a pih and the other of said support and margin having an opening in which said pin is removably disposed to locate the hood in a predetermined position on the stack.

6. An afterburner as claimed in claim 4, said gas supply means comprising a U-shaped tube with the lower edge of the hood disposed in the bend of the U.

7. An afterburner as claimed in claim 2, and a tube that extends through and is secured to the stack for conveying the blown pilot light toward said emerging fuel.

8. An afterburner as claimed in claim 7, said fuel tube terminating in an upwardly extending outlet, a relatively large upwardly concave deflector disc carried by and surrounding said outlet, and a relatively small downwardly concave disc disposed above said outlet, said tube for conveying the blown pilot light being secured adjacent its outer end in said wall of the stack and resting adjacent its inner end on said relatively large deflector disc. 

2. An afterburner as claimed in claim 1, said fuel supply means comprising a pair of orifices in parallel fluid circuit with each other, one of said orifices being larger than the other and supplying gas to said tube, and the said other orifice blowing across the pilot light.
 3. An afterburner as claimed in claim 2, and a downwardly opening annular hood encompassing said stack and covering said orifices and pilot light.
 4. An afterburner as claimed in claim 3, and means removably mounting said hood on the stack.
 5. An afterburner as claimed in claim 4, said removable mounting means comprising a support carried by the stack, the inner margin of the hood resting on said support, one of said support and margin having a pin and the other of said support and margin having an opening in which said pin is removably disposed to locate the hood in a predetermined position on the stack.
 6. An afterburner as claimed in claim 4, said gas supply means comprising a U-shaped tube with the lower edge of the hood disposed in the bend of the U.
 7. An afterburner as claimed in claim 2, and a tube that extends through and is secured to the stack for conveying the blown pilot light toward said emerging fuel.
 8. An afterburner as claimed in claim 7, said fuel tube terminating in an upwardly extending outlet, a relatively large upwardly concave deflector disc carried by and surrounding said outlet, and a relatively small downwardly concave disc disposed above said outlet, said tube for conveying the blown pilot light being secured adjacent its outer end in said wall of the stack and resting adjacent its inner end on said relatively large deflector disc. 